Ship-propulsion system



w. SCHOENI SHIP PROPULSION SYSTEM Filed Aug. a, 1928 May 23, 1933.

Inventor:

By I

.. tea-M 23,1933

UNITED STATES PATENT: OFFICE WALTER BGH OENI, OI BADEI N', SWITZERLAND, ASSIGNOB '10 AKTIENGESELLSOELIT BROWN DOVEBI & (FIE, 0! mm, SWITZERLAND, A .rom'r STOCK COIPANY OI BHIP-I'BDPULSION SYSTEI Application fled August 8, 1888, Serial Io. 298,314, and in Germany August 8, 1887.-

It has already been proposed to utilize the exhaust steam of piston steam engines, intended more particularly for driving ships propellers, in exhaust steam turbinesand to utilize the war of these exhaust steam turbines for -1ncreasing the power or for increasin the efliciency of the propeller drive. The ex aust steam turbines as a rule work on to the same propeller shaft as the piston steam engines and drive the said shaft di rectly or through the intermediary of a transmission gear. It has also been proposed to introduce betwwn the exhaust steam turbine and the propeller shaft drivenby the piston engine, electric transmission gear consisting of a' generator driven by the turbine and a motor fed bythe latter and mounted on the propeller shaft.

The invention relates to an arrangement of the latter kind and consists in this, that the reversal of the direction of revolution of the piston engine and of the motor is efi'ected simultaneously by the controlling gear of the former.

In the accompanying drawing a construe-- tionalexample of a reversing arrangement according to the present invention is shown.

K is the piston steam engine which drives the propeller shaft P on which the motor M is mounted and T is the exhaust steam turbine which drives the generator G feeding the motor M. The hand-operated lever U for reversing the piston steam engine at the same time forms the controllin lever for the double poleelectro-magnetica ly operated switches S S lying in the 'conductors connecting the generator and motor. The controlling lever is rovided with brushes which bridge overs 'ding contacts of an auxiliary circuit for controlling the switches S S When the piston engine is reversed by reversing the lever U from ahead to astern, through the sliding contacts being source of current. The particular switch becomes operative. and alters the current between the generator and motor whereby the direction of rotation of the motor is changed. The switch S may for instance bridged over, either the switch S or the switch S2 is connected to the auxiliary be used for going ahead and the switch S for going astern. In this way the generator and the exhaust steam turbine maintain their direction of rotation, that is to say the exhaust steam turbine always runs in the same direction, irrespective of whether the piston steam engine is running forwards or backwards.

The reversal in the direction of rotation of the-motor may be efiected for instance in the case of alternating current motors, by reversing the rotating field and in the case of continuous current motors by reversing the current in the rotor circuit. Fora slow running motor a three-phase asynchronous generator and an externally excited synchronous motor would preferably be used.

In order to prevent the electric motor be- 'ing reversed rematurel when the main engme is rapi y reverse the auxiliary circuit of the switches S and S is only closed by a centrifugal switch driven from the shaft of the piston steam engine, when the propeller shaft has approximately come to rest. In this way, even in the case of a rapid reversal, the electric motor will only-be re versed when the speed of revolution has sunk very low. The effect of this is that the reversal of the electric motor can only take place when there is ractically no load. The current impulse wlilich takes place on the reversal of the motor can be minimized, for instance by the field of the motor being weakened through a relay being 0 erated by a centrifugal switch driven from t e generator shaft, which relay connects up a resistance in the exciter circuit. In operation, when the speed of the generator shaft drops substantiall below normal speed, upon reversal of t e e e K, the centrifugal switch closes-,as sh d wn, to effect openin of the relay switch which is springiase to closed osition. The resistance. shown is then e ective to weaken the field of the motor M. When the generator shaft regains its normal speed the, relay switch is eenergized, as will be apparent, and the field resistance is therefore short-circuited.

The generator G will actually supply power to the'motor M for forward rotation after the lever U has been moved to the lefthand, astern position. This action, however, does not appreciably interfere with the described control action because it rsists for only a very short time, that is, a ew seconds which ela se while the engine K slows down to the point whereat the centrifugal switch associated with the shaft P is closed.

A similar controlling arrangement may be efiected in the case of ships having more than one shaft, an independent exhaust steam turbine set being preferably co-ordinated to each propeller shaft. In the ropulsion of ships by means of Diesel engines or other internal combustion iston engines, it is of course possible to use t e exhaust gas turbine in place of an exhaust steam turbine.

Having now particularly described and ascertained the nature of my said invention and in what manner the same is to be per-' formed, I declare that what I claim is 2-,-

. 1.. In a shi propulsion system, a I propeller shaft riven by a reversible engine and a reversible motor, a turbine driven by exhaust fluid from the engine and in driving relation with a generator for supplying current to the motor, a reversing at for the engine, switch means for control ing the su ply of current from the generator to t e motor, an auxiliary circuit interconnecting said reversin gear and said switch means, and a oentri ugal switch means indriving relation with said shaft 0 rative to rmit establishment of said auxiliary circuit only when the shaft has ap roximately come to rest from either direction of rotation.

2. In a ship propulsion stem, a propeller sh aft driven by a reversi le 'engineand a reversible motor, a turbine driven by exhaustfluid from the engine and in driving relation with agenerator'for supplying current to the motor, a reversing gear for the engine, switch means controlling the supply of current from the generator to the motor means interconnecting said reverse r and said switch means for changin the 'rection of rotation of said motor, asi means comprising a centrifugal switch actuated responsive to and in dependence upon the speed of rotation of the said nerator operative to vary the field excitation of said motor at times of reversal of. direction of rotation of the latter.

3. In a shi ropulsion system comprising a propeller s a a reversib e engine in driving relation with said shaft a reversing gear for said engine a turbine driven by exhaust fluid from engine, a generator driven by said turbine, a reversible motor in driving relation with said shaft and to be connected with said generator through said reversing switch means, means operable in dependence upon the speed of rotation of the said shaft e ective to control actuations ill of said switch means, and means amociated .cuit for sai said engine, means res with and operable. responsive to actuations of said reversing gear eifective upon actuations thereof to control reversing actuations of said switch means in dependence upon the o rative actuations of the said means opera Is in dependence upon the speed of rotation of the said shaft.

4. In a ship-propulsion system, an engine, a motor, a turbine, a connection-supplying said turbine with the exhaust from said engine, a propeller shaft, said engine and said motor being in direct driving relation with respect to said shaft, a generator driven by said turbine for supplying said motor, switch means for reversing the operating connections between said generator and said motor, a control circuit for said switch means, a member for "efiectin reversal of said engine, a centrifu al switc driven by the propeller shaft an forming part of said control circuit, and switch means forming part of said control circuit and controlled by said member.

5. In a ship-propulsion system, an engine, a motor, a turbine, a connection supplying said turbine with the exhaust from said en 'ne, a propeller shaft, said engine and sai motor being in direct driving relation with respect to said shaft, a genera tor driven by said turbine for supplying said motor, switch means for reversing the operating connections between said generator and said motor, electromagnets for effecting respectively operation of said switch means in o osite senses, an excitation cirelectromagnets, a centrifugal switch driven by the propeller shaft and forming part of said circuit, a member for efiecting reversal of said engine, and switch means controlled by said member for connecting said electromagnet selectively in said circuit.

6. In a shipropulsion system, an engine,

a motor, a tur ine, a connection suppl ing said turbine with the exhaust from sai engine, a propeller shaft, said engine and said motor being in direct driving relation with respect to said shaft, a generator driven by said turbine for supp ying said motor, switch meansfor effecting reversal of said motor, a control circuit for said switch means, a member for effecting reversal of nsive to speed conditions of said shaft a ve a predetermined rate and operable at such conditions to render said switch means non-effective for the motor-reversing action thereof, and switch means forniin part of said control circuit and controlle by said member.

In testimony whereof I have hereunto.

subscribed my name this day of July A. D. 1928.

WALTER SCHOENI. 

